EV terms, in plain English
Battery degradation and warranty
EV batteries gradually lose some capacity with age and use. The battery warranty tells you what the manufacturer will cover if that loss becomes excessive.
Battery degradation is a gradual loss of usable capacity, not the same thing as a sudden battery failure.
As an EV battery ages, it may hold a little less energy than when it was new. If a car that once delivered 400 km in similar conditions later delivers 380 km, part of the difference may be degradation. Temperature, driving conditions and tyre changes can also affect the number you see.
The car’s battery-management system helps protect the battery by controlling temperature, charging and how much of the total capacity you can use.
Battery warranties are usually separate from the general vehicle warranty. They often run for more years and kilometres, and many include a minimum retained-capacity promise. The period, kilometre limit, capacity threshold, exclusions and transfer rules vary by manufacturer.
If you’re buying a used EV, check the remaining battery warranty and ask for a battery state-of-health report where one is available. Service history and any conditions attached to warranty transfer also matter.
Why it matters: a small amount of capacity loss is normal. What matters is the battery’s current health, whether the remaining range suits you and exactly what the warranty covers if degradation is greater than expected.
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